Coronavirus live updates: As coronavirus hospitalizations climb, Trump sidelines health advisors

The World Health Organization on Thursday updated its description of how the coronavirus spreads, noting that it may linger in the air — particularly in indoor settings with poor ventilation — and calling for more research.

The tweak came days after a group of more than 200 scientists from over 30 countries publicly urged the United Nations health agency to consider growing evidence of airborne transmission.

Most public health guidelines focus on transmission by close or direct contact and recommend social distancing measures and regular hand-washing. This remains the focus of the WHO guidance.

But in a July 9 update, the WHO notes reports of outbreaks in “closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking, or singing” — without saying outright that airborne transmission is taking place.

“Research on airborne transmission is growing but the evidence is not definitive. Airborne transmission in crowded, closed and poorly ventilated settings cannot be ruled out. However, the evidence needs to be gathered and interpreted,” Ashley Baldwin, a WHO communications officer, said in an emailed statement.

Donald Milton, a professor of environmental health at the University of Maryland and one of the scientists who wrote to the WHO, said he was disappointed the WHO stopped short of acknowledging the evidence of airborne transmission. He said, though, that he is glad it addressed the need for better indoor ventilation.

Another signatory, Jose-Luis Jimenez, a chemist at the University of Colorado, said the updated WHO description was “a move in the right step, albeit a small one.”

“It is becoming clear that the pandemic is driven by super-spreading events, and that the best explanation for many of those events is aerosol transmission,” he said. “WHO’s slow motion on this issue is unfortunately slowing the control of the pandemic.”